1. Field of the Invention
The present invention relates to a method and apparatus for molding a case used in an information detection hole system, in which the presence of an identification hole formed in the case, the position of the identification hole, and the form of the identification hole are detected in order to obtain specified information relating to the case.
2. Related Art
An information detection hole system refers, for example, to a system in which specified information such as the storage capacity and data write feasibility of a magnetic disk housed in a microfloppy disk case (disk cartridge) can be detected according to the presence of the identification hole provided at a prescribed position on the case. The microfloppy disk is configured such that a thin magnetic disk is rotatably stored inside a thin rectangular case. This case is comprised of a pair of shallow box-like case halves which are synthetic resin molds and. Heretofore, these microfloppy disk cases have been developed with common external dimensions, and classified according to storage capacity into the 1MB (megabyte) type, 2MB type, 4MB type, etc. The respective identification holes are provided at prescribed positions on the cases for the purposes of identifying the respective types (storage capacities), and for the purposes of permitting/inhibiting data writing onto the magnetic disks (to prevent mistaken erasures). The identification hole for permitting/inhibiting data writing is configured to be capable of being opened and closed so as to permit the changing of the state of permitting/inhibiting data writing at appropriate times.
Accordingly, in the case where this microfloppy disk case is manufactured, it is necessary to change the setting of the cavity of the mold of the molding machine according to the-type of storage capacity, so that the respective identification holes for type identification and for data writing permission/inhibition are formed in the prescribed positions. In this case, when one adopts a case molding method where a dedicated mold is prepared for each type, and a dedicated mold is set in the molding machine corresponding to the type to be manufactured, one must successively repeat troublesome operations involving the removal of the mold from the molding machine, the disassembly/assembly of the mold, and the attachment of the mold to the molding machine whenever the type to be manufactured is changed, and the rate of operation markedly drops. Furthermore, by increasing the number of the types of mold to be prepared, there is a problem that equipment costs increase, leading to a rise in production costs.
Therefore, as disclosed in Japanese Utility Model Unexamined Publication No. Hei-2-146013 and Japanese Patent Unexamined Publication No. Hei-5-212752, a forming method has been proposed wherein the mold product part defining the cavity is made common to the respective type, and the bush element which projects into the interior of the cavity for the purposes of forming the identification holes is removably attached. Only the bush elements need be prepared according to the respective storage capacity types, and the bush elements are replaced when changing the type of the case to be produced. Thus, by means of a case forming method which enables matching with each type by replacement of the bush elements alone, it is necessary to prepare only one kind of mold, so that it is possible to mitigate equipment costs and seek the reduction of production costs.
In the case forming method disclosed in the aforementioned Japanese Utility Model Unexamined Publication No. Hei-2-146013, the bush elements designed to form the identification holes are removably attached to the core mold. In this case, since a configuration is adopted where the bush elements are attached or removed from the mold attachment face of the core mold (the face at the opposite side to the cavity side), when replacing the bush elements for the purposes of changing the type to be produced, it is necessary to expose the mold attachment face of the core mold by removing the core mold from the core receiving plate of the molding machine. Thus, in the final analysis, the aforementioned proposal could not resolve the conventional problem. It is still necessary to successively repeat troublesome operations involving the removal of the mold from the molding machine, the disassembly/assembly of the mold, and the attachment of the mold to the molding machine whenever the type to be manufactured is changed; thus, the rate of operation is still low.
On the other hand, in the case of Japanese Patent Unexamined Publication Hei-5-212752, the bush elements designed to form the identification holes are attached to a cavity mold which is a fixed mold. The bush elements are attached to the cavity mold in such a way that they can be freely slipped on and off from the back side of the cavity mold, and are fixed in place by the pressure of pressers which are provided in the fixed side receiving plate supporting the cavity mold. Furthermore, the fixed side receiving plate is constituted by two receiving plate members. A first fixed side receiving plate member is positioned on the cavity mold side and which has through holes into which the pressers are inserted. A second fixed side receiving plate member is positioned on the fixed block side of the molding machine and which prevents the removal of the pressers that are inserted into the first fixed side receiving plate member. These two fixed side receiving plate members are made capable of mutual separation by a bolt which is removably attached from the parting face between the cavity mold and the core mold.
That is, in the case of Japanese Patent Unexamined Publication No. Hei-5-212752, by opening the cavity mold and the core mold and by removing from the parting face side the bolt which fixes the first and second fixed side receiving plate members, it becomes possible to replace the bush elements while the cavity mold itself is attached to the molding machine, and compared to the case of the aforementioned Japanese Utility Model Unexamined Publication No. Hei-2-146013, the work operations at the time of bush element replacement are greatly reduced.
However, in the case of this Japanese Patent Unexamined Publication No. Hei-5-212752, the use of two fixed side receiving plate members leads to the complication of the configuration. There is a problem that it is necessary to conduct the labor of separating the two fixed side receiving plate members in order to replace the bush elements, and that it becomes proportionately difficult to improve the rate of operation.
In order to minimize the labor involved in the replacement of the bush elements, a configuration is also being researched wherein attachment pieces which project along the parting face between the cavity mold and the core mold are provided in the respective bush elements that form the identification holes, and wherein these attachment pieces are directly screwed on the back of one of the metal molds outside the cavity region.
In this type of configuration, on the back of the mold to which the attachment pieces are to be fixed, grooves are formed into which the attachment pieces are fitted. Slight differences in grade remain along the contour into which the attachment pieces fit, and a problem has been pointed out that this forms a mark on the rear of the molded case-half which damages the external appearance of the case.